Wait, I did wha? -- NOOOOOOOOOOOO!

March 23, 2012 7:44 AM

I just erased a disk (not reformatted). It was the wrong one. How can I undo this horrible thing I did, if at all possible?

Pertinent details: MacOS X 10.6.8, used Disk Utility's basic "erase" function, external drive Seagate GoFlex 2T USB.

posted by hippybear to computers & internet (9 answers total)

Ah, also drive was formatted Mac OS Extended Journaled, if that matters.
posted by hippybear at 7:54 AM on March 23, 2012

I think this software would be your best bet. Be sure to only connect your disk when you are going to attempt recovery, to try and preserve as much information as possible.
posted by NordyneDefenceDynamics at 8:09 AM on March 23, 2012 [1 favorite]

I agree with NordyneDefenceDynamics, the easiest solution to your problem is to buy a copy of Prosoft's Data Rescue for Mac. It may not be able to recover all of the files that were on the drive at the time you erased it, but there is a good chance that it will be able to recover most of them. Keep the external drive offline until you're ready to attempt to recover the data.

You'll need another drive with sufficient available space to hold the recovered files (Data Rescue needs to store the recovered files on a drive other than the damaged source drive). Consider buying an additional external drive for this purpose, and then, after your data has been recovered, repurpose one of your two external drives as a Time Machine backup drive.
posted by RichardP at 8:19 AM on March 23, 2012

Your data is still there, or most of it is, which is good. However, all the file system information about where it is has been deleted, which is bad. (Unless you checked one of the security options other than "Don't erase data")

If you want to try some recovery yourself, I would first try PhotoRec, which is free. There are other commercial tools as well, . You will need a second drive to copy to, and you may lose all the file names. :(
posted by procrastination at 8:22 AM on March 23, 2012

Yeah, the drive was unplugged shortly after I discovered my error, with the only access to it being one viewing of the Finder window for it to discover that it was, indeed, all gone.

Interesting to know about needing another drive. That's good advice.

And yes, I do have a Time Machine drive already, but I haven't been using it to backup my external drives (I have four) because 1) they're huge, and 2) they're external, and 3) they aren't really mission critical like the internal drive on my computer is.

I don't even know if I could purchase a drive large enough to back up all my hard drives as a single Time Machine backup, honestly. I know they make them, but I couldn't possibly afford one.

I can't afford a new hard drive or software until next week, so I'll have to just wait until then.

Still, looking for more suggestions if there are any out there.

I feel so stupid for having done this. *weeps softly to himself*
posted by hippybear at 8:34 AM on March 23, 2012

I *just* did this a month ago, so I feel you. PhotoRec worked for me, though I muddled through the process with much trepidation. I was never sure how many 'passes' the program would need to make. (I quit after about 40, and several days straight of recovery processing.) Also, the recovered files come out with weird titles and getting everything back to the way it was, with metadata and file names in place has been just as big an ordeal.

Seconding everyone who's said to make sure you have a new/other drive with similar or greater capacity than the one you're trying to recover.

Lemme know if you want to commiserate and/or compare notes.
posted by carsonb at 8:50 AM on March 23, 2012

Data Rescue has worked great for me, although not in this exact case.

I know people who have done this exact thing in a recording studio, with big budget major label artists, if that makes you feel any better.
posted by bongo_x at 11:04 AM on March 23, 2012

but I haven't been using it to backup my external drives (I have four)

Any data that you don't want to lose has to exist, at minimum, on two different physical drives†. Otherwise you are one hardware failure, user error, software fault, or file corruption away from losing that data permanently. I don't say this in an I-told-you-so way, or to rub it in. I say this because if you have any important data on those other three external drives you need to find a way to back those up. If size of drives and budget prevent you from making full backups of those drives at the very least make sure you copy any important data to another drive.

You can set Time Machine to backup an external drive but then exclude most of the drive except the most important folders if you don't have space to backup everything. Eg, let's say you have an external drive with music, movies, photos, and documents, but decide that the critical things are the photos and documents. You can then exclude the music and movies folders from the backup.

† Two different physical drives is the minimum and, assuming those drives are in the same location, still doesn't protect against theft, fire, flood, other disasters. What I do is keep a drive at my parents' house and when I'm there, about once a year, will do a clone of my system drive. So in my worst case scenario I at least have all important files greater than a year old. This drive is in addition to my local Time Machine backup drive, which I backup to every week.
posted by 6550 at 11:07 AM on March 23, 2012

I never buy one drive anymore, always two of the same size. I have most data synced between my laptop and desktop, and two backups for each. That's six copies and I still don't feel comfortable. In case you can't tell, I've had a few bad experiences with data loss.
posted by bongo_x at 6:15 PM on March 23, 2012 [1 favorite]